The present disclosure relates to a sheet transport device for transporting sheets, for suitably use in an image forming apparatus such as a copier or a printer.
A sheet transport device having a tray for accommodating a number of sheets, and adapted to transport the sheets from the tray is incorporated in an image forming apparatus such as a copier, a printer, a facsimile machine, or a complex machine having the functions of these devices. In the image forming apparatus, the sheet transport device is provided with a sheet storing portion for storing sheets. The sheets stored in the sheet storing portion are dispensed one by one from the sheet storing portion and transported for forming an image on each of the sheets in a main body of the image forming apparatus.
In the thus constructed sheet transport device, the sheet storing portion has a cassette structure which is configured to be detachably attachable to the apparatus main body. The sheet storing portion has a guide member for restricting displacement of a sheet in a sheet width direction for stabilizing sheet transport. The guide member is movable in the sheet width direction. With this arrangement, the position of the guide member is adjusted for transporting various types of sheets.
In a conventional sheet transport device, as shown in a top plan view of FIG. 19, a sheet is disposed at the sheet position P1 in a sheet tray 500 as a sheet storing portion in a state that the position of the sheet in the sheet width direction is restricted by guide members 520. A pickup roller 310 is contacted with a right end of the sheet for feeding the sheet toward a sheet transport path. Further, a sheet feeding roller 320 for separating the sheet from other sheets, and a transport roller 330 for transporting the sheet separated from the other sheets by the sheet feeding roller 320 further toward the sheet transport path are disposed on the right side (downstream side in the sheet transport direction) of the pickup roller 310. When an image forming operation is being carried out in the image forming apparatus, transport of the sheet fed out from the sheet tray 500 may be stopped by e.g. a sheet jam in a state that a leading end of the sheet is stuck in the vicinity of a sheet feeding nip portion A formed by the sheet feeding roller 320. In the case where a user tries to pull out the sheet tray 500 in the arrow D1A direction in the above condition, the sheet at the sheet position P1 may be pushed in the arrow D1A direction by the guide members 520, and at the same time, may receive a pivotal force as indicated by the arrow R1 direction, because the sheet is nipped near the sheet feeding nip portion A. By application of the pivotal force, the sheet may be pushed and displaced to the sheet position P2, and may hit against a post frame 231 of the apparatus body. As a result, a part of the sheet may be left in the image forming apparatus while forming creases in the sheet, without being pulled out together with the sheet tray 500. In a worse case, the sheet may be damaged or torn.
In view of the above, an object of the present disclosure is to provide an arrangement capable of preventing a likelihood that a sheet may be stuck between a sheet tray and an apparatus main body, and may be damaged or torn, with a part of the sheet being left in the apparatus main body, even if a sheet tray is pulled out of the apparatus main body in a state that a leading end of the sheet has been fed out in a sheet transport path from the sheet tray.